(1) Field of the Invention
The present invention relates to a structure of a vibration-proof rubber bushing used for supporting a vibration-proof material of such as a suspension of an automotive vehicle.
(2) Description of the Background Art
For example, a compression rod bushing has often been used to support a compression rod installed on one end of a transverse link of an automotive vehicle on a vehicle body.
The compression rod bushing described above is exemplified by a Japanese Patent Application First Publication Showa 61-223344 published on Oct. 3, 1986.
The compression rod bushing is formed with a U-shaped of cross section and is made of a rubber material. An inserting hole for inserting the compression rod thereinto is provided in its inner portion.
Hence, in a case where the compression rod is vibrated in its axial direction or in a direction transverse to the axial direction, the rubber material of the bushing absorbs the vibration described above to achieve an improvement in its shimmy prevention performance.
The structure of the compression rod bushing described above is advantageous in that the transverse link can elastically be supported by a mere insertion of the compression rod into the bushing. However, it has a problem in that in the case where a single kind of rubber material is used, a limit is present in increasing a loss factor (to be described later) so that a desired vibration-proof characteristic cannot be achieved.
On the other hand, although a relatively high loss factor can be achieved if a plurality of rubber materials are blended, a desired durability for the bushing cannot be achieved.